In clojure.contrib.duck-streams append-spit writes out encoding
markers (for UnicodeLittle for example this is a FEFF in hex)
each time it appends to a file. This should happen only when
the file is initially created.

stu said: I am not sure there is a good answer here. The code above chooses an encoding with an explicit marker, and gets what it asks for.

One proposed solution (http://github.com/sergey-miryanov/clojure-contrib/commits/bug-30) tries to detect this scenario, and recover via a hard-coded mapping between encodings-with-markers and similar-encodings-without. But I don't think this can work in general, because the set of possible encodings is open and the Charset API doesn't provide a mapping between the with-markers and without-markers versions.

Sorry, and please feel free to reopen this if I am missing an obvious approach.